情态动词 must 的基本用法：
(1) 表示义务、命令或必要，意为“必须” mustn’t 表示禁止，意为“不许、不可以”。
如： Everyone must attend the lecture. You mustn lend it to others.
(2) 表示推测，意为“一定” 一般用于肯定句
如： The light is still on, so he must be at home.
(3) must 开头的疑问句：
肯定回答用 must 否定回答则常用 needn’t(不需要，不必)，相当于 don’t have to
— Must I finish the project today? —No, you needn’t.
情态动词 have to 的基本用法：
(1) have to 作为情态动词，意为“必须、不得不”，侧重于客观上的必要 You have to wear sports shoes for gym class.
(2) 基本句式结构： 主语+have/has to+动词原形+其他.
主语+don’t/doesn’t have to+其他.
Do/Does+主语+have to+动词原形+其他 ?
Tony has to play the guitar every afternoon.
Nick doesn’t have to wear a uniform.
Do you have to stay at home on weekends?
情态动词 must 与 have to 的区别：
(1) must 表说话人的主观看法， have to 表客观需要 I must leave at six today. I have lost my pen, so I have to buy one.
(2) must 只有一种形式 have to 有更多的形式：have to, has to, had to, will have to 等 I thought I must go there. He had to look after his sister yesterday.
